*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
/*清楚间距*/
.clearfix:before,
.clearfix:after{
    content: "";
    display: block;
    clear: both;
}
/*清楚浮动*/
.wrapper{
    width: 1200px;
    margin: 0 auto;
}
/*加宽水平居中*/
.wwl{
    width: 33.333333%;
    height: 100px;
    background-color:lawngreen;
    float: left;
    color: red;
}
/*内容的样式*/

body{
    background-color:lightpink;
}

/*响应式的代码*/
/*1.改变主体内容的宽度*/
/*2.改变布局的宽度*/
@media (max-width: 600px) {
    .wrapper{
        width: 90%;
    }
    .wwl{
        width: 100%;
        color: blue;
        text-align: center;
        font: 20px/20px 华文行楷;
    }
    body{
        background-color:lightblue;
    }
}

